Dynamic Range Control/Compression (DRC) reduces the dynamic range of an audio signal by some amount by (1) making soft parts in the audio signal louder; (2) making loud parts in the audio signal softer; or (3) both making soft parts louder and making loud parts softer. A reduced dynamic range may be desirable in several situations, including for audio playback systems that can only reproduce a small dynamic range while maintaining low distortions, listening environments with distracting sounds, and in situations where the listener does not want to distract others. DRC may also be applied to avoid clipping, i.e., exceeding the full scale of the audio format, for instance when audio samples are represented as fixed-point numbers. Another application of time-varying gain is the generation of fade-in and fade-out of the audio content at the beginning and end of a song for so-called gap-less content.
The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section.